Authentication fail. #18

when i use demo codes python, nodejs for API 4.0 result:
{"error": {"code": 11, "message": "Authentication fail."}, "result": null, "id": 4041}

The algorithm sign params is wrong?
Code python:
def get_sign(secret_key, message):
h = (base64.b64encode(hmac.new(secret_key.encode('utf-8'), message.encode('utf-8'), hashlib.sha512).digest())).decode()

Code nodejs:
function getSign(str) {
return crypto.createHmac('sha512', SECRET).update(str).digest().toString('base64');